Polyacrylamide: Difference between revisions
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| ImageSize = 150 | | ImageSize = 150 | ||
| IUPACName = poly(2-propenamide) | | IUPACName = poly(2-propenamide) | ||
| SystematicName = | | SystematicName = | ||
| OtherNames = poly(2-propenamide), poly(1-carbamoylethylene) | | OtherNames = poly(2-propenamide), poly(1-carbamoylethylene) | ||
|Section1={{Chembox Identifiers | |Section1={{Chembox Identifiers | ||
| ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}} | | ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}} | ||
| ChemSpiderID = none | | ChemSpiderID = none | ||
| Abbreviations = | | Abbreviations = | ||
| CASNo = 9003-05-8 | | CASNo = 9003-05-8 | ||
| CASNo_Ref = {{cascite|correct|CAS}} | | CASNo_Ref = {{cascite|correct|CAS}} | ||
| Line 17: | Line 17: | ||
| UNII1 = 5D6TC4BRWV | | UNII1 = 5D6TC4BRWV | ||
| UNII1_Comment = (1500 MW) | | UNII1_Comment = (1500 MW) | ||
| EINECS = | | EINECS = | ||
| PubChem = | | PubChem = | ||
| SMILES = | | SMILES = | ||
| InChI = | | InChI = | ||
| RTECS = | | RTECS = | ||
| MeSHName = | | MeSHName = | ||
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| ChEBI = | | ChEBI = | ||
| KEGG_Ref = {{keggcite|correct|kegg}} | | KEGG_Ref = {{keggcite|correct|kegg}} | ||
| KEGG = | | KEGG = | ||
}} | }} | ||
|Section2={{Chembox Properties | |Section2={{Chembox Properties | ||
| Formula = (C<sub>3</sub>H<sub>5</sub>NO)<sub>n</sub> | | Formula = (C<sub>3</sub>H<sub>5</sub>NO)<sub>n</sub> | ||
| MolarMass = | | MolarMass = | ||
| Appearance = | | Appearance = | ||
| Density = | | Density = | ||
| MeltingPt = | | MeltingPt = | ||
| MeltingPt_notes = | | MeltingPt_notes = | ||
| BoilingPt = | | BoilingPt = | ||
| BoilingPt_notes = | | BoilingPt_notes = | ||
| Solubility = | | Solubility = | ||
| SolubleOther = | | SolubleOther = | ||
| Solvent = | | Solvent = | ||
| LogP = | | LogP = | ||
| VaporPressure = | | VaporPressure = | ||
| HenryConstant = | | HenryConstant = | ||
| AtmosphericOHRateConstant = | | AtmosphericOHRateConstant = | ||
| pKa = | | pKa = | ||
| pKb = }} | | pKb = }} | ||
|Section3={{Chembox Structure | |Section3={{Chembox Structure | ||
| CrystalStruct = | | CrystalStruct = | ||
| Coordination = | | Coordination = | ||
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|Section4={{Chembox Thermochemistry | |Section4={{Chembox Thermochemistry | ||
| DeltaHf = | | DeltaHf = | ||
| DeltaHc = | | DeltaHc = | ||
| Entropy = | | Entropy = | ||
| HeatCapacity = }} | | HeatCapacity = }} | ||
|Section5={{Chembox Pharmacology | |Section5={{Chembox Pharmacology | ||
| AdminRoutes = | | AdminRoutes = | ||
| Bioavail = | | Bioavail = | ||
| Metabolism = | | Metabolism = | ||
| HalfLife = | | HalfLife = | ||
| ProteinBound = | | ProteinBound = | ||
| Excretion = | | Excretion = | ||
| Legal_status = | | Legal_status = | ||
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| Pregnancy_category = | | Pregnancy_category = | ||
| Pregnancy_AU = | | Pregnancy_AU = | ||
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|Section6={{Chembox Explosive | |Section6={{Chembox Explosive | ||
| ShockSens = | | ShockSens = | ||
| FrictionSens = | | FrictionSens = | ||
| DetonationV = | | DetonationV = | ||
| REFactor = }} | | REFactor = }} | ||
|Section7={{Chembox Hazards | |Section7={{Chembox Hazards | ||
| ExternalSDS = | | ExternalSDS = | ||
| MainHazards = | | MainHazards = | ||
| NFPA-H = | | NFPA-H = | ||
| NFPA-F = | | NFPA-F = | ||
| NFPA-R = | | NFPA-R = | ||
| NFPA-S = | | NFPA-S = | ||
| HPhrases = | | HPhrases = | ||
| PPhrases = | | PPhrases = | ||
| GHS_ref = | | GHS_ref = | ||
| FlashPt = | | FlashPt = | ||
| AutoignitionPt = | | AutoignitionPt = | ||
| ExploLimits = | | ExploLimits = | ||
| LD50 = | | LD50 = | ||
| PEL = }} | | PEL = }} | ||
|Section8={{Chembox Related | |Section8={{Chembox Related | ||
| OtherAnions = | | OtherAnions = | ||
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| OtherCompounds = }} | | OtherCompounds = }} | ||
}} | }} | ||
| Line 101: | Line 101: | ||
== Physicochemical properties == | == Physicochemical properties == | ||
Polyacrylamide is a [[polyolefin]]. It can be viewed as [[polyethylene]] with amide substituents on alternating carbons. Unlike various [[nylon]]s, polyacrylamide is not a [[polyamide]] because the amide groups are not in the polymer backbone. Owing to the presence of the amide (CONH<sub>2</sub>) groups, alternating carbon atoms in the backbone are [[stereogenic]] ( | Polyacrylamide is a [[polyolefin]]. It can be viewed as [[polyethylene]] with amide substituents on alternating carbons. Unlike various [[nylon]]s, polyacrylamide is not a [[polyamide]] because the amide groups are not in the polymer backbone. Owing to the presence of the amide (CONH<sub>2</sub>) groups, alternating carbon atoms in the backbone are [[stereogenic]] (chiral). For this reason, polyacrylamide exists in atactic, syndiotactic, and isotactic forms, although this aspect is rarely discussed. The polymerization is initiated with radicals and is assumed to be stereorandom.<ref name=Ull/> | ||
===Copolymers and modified polymers=== | ===Copolymers and modified polymers=== | ||
Linear polyacrylamide is a water-soluble polymer. Other polar solvents include [[DMSO]] and various alcohols. [[Cross-link]]ing can be introduced using [[N,N'-Methylenebisacrylamide|N,N-methylenebisacrylamide]]. Some crosslinked materials are swellable but not soluble, i.e., they are [[hydrogel]]s. | Linear polyacrylamide is a water-soluble polymer. Other polar solvents include [[DMSO]] and various alcohols. [[Cross-link]]ing can be introduced using [[N,N'-Methylenebisacrylamide|N,N-methylenebisacrylamide]]. Some crosslinked materials are swellable but not soluble, i.e., they are [[hydrogel]]s.{{cn|date=September 2025}} | ||
Partial hydrolysis occurs at elevated temperatures in aqueous media, converting some amide substituents to carboxylates. This hydrolysis thus makes the polymer particularly hydrophilic. The polymer produced from N,N-dimethylacrylamide resists hydrolysis. | Partial hydrolysis occurs at elevated temperatures in aqueous media, converting some amide substituents to carboxylates. This hydrolysis thus makes the polymer particularly hydrophilic. The polymer produced from N,N-dimethylacrylamide resists hydrolysis.{{cn|date=September 2025}} | ||
Copolymers of [[acrylamide]] include those derived from acrylic acid. | Copolymers of [[acrylamide]] include those derived from acrylic acid.{{cn|date=September 2025}} | ||
==Uses== | ==Uses== | ||
In the 1970s and 1980s, the proportionately largest use of these polymers was in water treatment.<ref>{{Cite web|url = | In the 1970s and 1980s, the proportionately largest use of these polymers was in water treatment.<ref>{{Cite web|url = https://www.nlm.nih.gov/toxnet/index.html | archive-url = https://web.archive.org/web/20171230230215/https://toxnet.nlm.nih.gov/cgi-bin/sis/search2/r?dbs+hsdb:@term+@rn+@rel+9003-05-8| archive-date = 30 December 2017 |title = Polyacrylamide|date = February 14, 2003|access-date = November 30, 2013|publisher = United States National Library of Medicine|at = Consumption Patterns|id = CASRN: 9003-05-8|url-status = live |website = Hazardous Substances Data Bank}}</ref> The next major application by weight is additives for [[pulp (paper)|pulp]] processing and [[papermaking]]. About 30% of polyacrylamide is used in the oil and mineral industries.<ref name=Ull/> | ||
===Flocculation=== | ===Flocculation=== | ||
One of the largest uses for polyacrylamide is to [[flocculation|flocculate]] solids in a liquid. This process applies to [[water treatment]], and processes like [[paper mill|paper making]] and screen printing. Polyacrylamide can be supplied in a powder or liquid form, with the liquid form being subcategorized as solution and emulsion polymer. | One of the largest uses for polyacrylamide is to [[flocculation|flocculate]] solids in a liquid. This process applies to [[water treatment]], and processes like [[paper mill|paper making]] and screen printing. Polyacrylamide can be supplied in a powder or liquid form, with the liquid form being subcategorized as solution and emulsion polymer.{{cn|date=September 2025}} | ||
Even though these products are often called 'polyacrylamide', many are actually [[copolymer]]s of [[acrylamide]] and one or more other species, such as an [[acrylic acid]] or a salt thereof. These copolymers have modified wetting and swellability. | Even though these products are often called 'polyacrylamide', many are actually [[copolymer]]s of [[acrylamide]] and one or more other species, such as an [[acrylic acid]] or a salt thereof. These copolymers have modified wetting and swellability.{{cn|date=September 2025}} | ||
The ionic forms of polyacrylamide has found an important role in the potable [[water industry|water treatment industry]]. Trivalent metal salts, like [[ferric chloride]] and [[aluminum chloride]], are bridged by the long polymer chains of polyacrylamide. This results in significant enhancement of the [[flocculation]] rate. This allows [[water purification|water treatment]] plants to greatly improve the removal of total organic content (TOC) from raw water. | The ionic forms of polyacrylamide has found an important role in the potable [[water industry|water treatment industry]]. Trivalent metal salts, like [[ferric chloride]] and [[aluminum chloride]], are bridged by the long polymer chains of polyacrylamide. This results in significant enhancement of the [[flocculation]] rate. This allows [[water purification|water treatment]] plants to greatly improve the removal of total organic content (TOC) from raw water.{{cn|date=September 2025}} | ||
=== Fossil fuel industry === | === Fossil fuel industry === | ||
{{main|Enhanced oil recovery}} | {{main|Enhanced oil recovery}} | ||
In the oil and gas industry, polyacrylamide derivatives (especially co-polymers) have a substantial effect on production by enhanced oil recovery by viscosity enhancement. High viscosity aqueous solutions can be generated with low concentrations of polyacrylamide polymers, which are injected to improve the economics of conventional water-flooding. In a separate application, [[hydraulic fracturing]] benefits from drag reduction resulting from injection of these solutions. These applications use large volumes of polymer solutions at concentration of 30–3000 mg/L.<ref name=clean>{{cite journal |title=Polyacrylamide Degradation and Its Implications in Environmental Systems| vauthors = Xiong B, Loss RD, Shields D, Pawlik T, Hochreiter R, Zydney AL, Kumar M |journal= Clean Water|volume=1|year=2018| issue = 1 | | In the oil and gas industry, polyacrylamide derivatives (especially co-polymers) have a substantial effect on production by enhanced oil recovery by viscosity enhancement. High viscosity aqueous solutions can be generated with low concentrations of polyacrylamide polymers, which are injected to improve the economics of conventional water-flooding. In a separate application, [[hydraulic fracturing]] benefits from drag reduction resulting from injection of these solutions. These applications use large volumes of polymer solutions at concentration of 30–3000 mg/L.<ref name=clean>{{cite journal |title=Polyacrylamide Degradation and Its Implications in Environmental Systems| vauthors = Xiong B, Loss RD, Shields D, Pawlik T, Hochreiter R, Zydney AL, Kumar M |journal= Clean Water|volume=1|year=2018| issue = 1 | article-number = 17 |doi=10.1038/s41545-018-0016-8|s2cid=135203788 |doi-access=free| bibcode = 2018npjCW...1...17X }}</ref> | ||
===Soil conditioning=== | ===Soil conditioning=== | ||
{{main|soil conditioner}} | {{main|soil conditioner}} | ||
The primary functions of polyacrylamide soil conditioners are to increase soil tilth, aeration, and porosity and reduce compaction, dustiness and water run-off. Typical applications are 10 mg/L, which is still expensive for many applications.<ref name=clean/> Secondary functions are to increase plant vigor, color, appearance, rooting depth, and emergence of seeds while decreasing water requirements, diseases, erosion and maintenance expenses. FC 2712 is used for this purpose. | The primary functions of polyacrylamide soil conditioners are to increase soil tilth, aeration, and porosity and reduce compaction, dustiness and water run-off. Typical applications are 10 mg/L, which is still expensive for many applications.<ref name=clean/> Secondary functions are to increase plant vigor, color, appearance, rooting depth, and emergence of seeds while decreasing water requirements, diseases, erosion and maintenance expenses. FC 2712 is used for this purpose.{{cn|date=September 2025}} | ||
===Molecular biology laboratories=== | ===Molecular biology laboratories=== | ||
| Line 135: | Line 135: | ||
=== Mechanobiology === | === Mechanobiology === | ||
The elastic modulus of polyacrylamide can be changed by varying the ratio of monomer to cross-linker during the fabrication of polyacrylamide gel.<ref>{{cite journal | vauthors = Denisin AK, Pruitt BL | title = Tuning the Range of Polyacrylamide Gel Stiffness for Mechanobiology Applications | journal = ACS Applied Materials & Interfaces | volume = 8 | issue = 34 | pages = 21893–21902 | date = August 2016 | pmid = 26816386 | doi = 10.1021/acsami.5b09344 }}</ref> This property makes polyacrylamide useful in the field of [[mechanobiology]], as a number of cells respond to mechanical stimuli.<ref>{{cite journal | vauthors = Pelham RJ, Wang Y | title = Cell locomotion and focal adhesions are regulated by substrate flexibility | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 94 | issue = 25 | pages = 13661–13665 | date = December 1997 | pmid = 9391082 | pmc = 28362 | doi = 10.1073/pnas.94.25.13661 | bibcode = 1997PNAS...9413661P | doi-access = free }}</ref> | The elastic modulus of polyacrylamide can be changed by varying the ratio of monomer to cross-linker during the fabrication of polyacrylamide gel.<ref>{{cite journal | vauthors = Denisin AK, Pruitt BL | title = Tuning the Range of Polyacrylamide Gel Stiffness for Mechanobiology Applications | journal = ACS Applied Materials & Interfaces | volume = 8 | issue = 34 | pages = 21893–21902 | date = August 2016 | pmid = 26816386 | doi = 10.1021/acsami.5b09344 | bibcode = 2016AAMI....821893D }}</ref> This property makes polyacrylamide useful in the field of [[mechanobiology]], as a number of cells respond to mechanical stimuli.<ref>{{cite journal | vauthors = Pelham RJ, Wang Y | title = Cell locomotion and focal adhesions are regulated by substrate flexibility | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 94 | issue = 25 | pages = 13661–13665 | date = December 1997 | pmid = 9391082 | pmc = 28362 | doi = 10.1073/pnas.94.25.13661 | bibcode = 1997PNAS...9413661P | doi-access = free }}</ref> | ||
===Niche uses=== | ===Niche uses=== | ||
The polymer is also used to make Gro-Beast toys, which expand when placed in water, such as the [[Test Tube Aliens]]. Similarly, the absorbent properties of one of its copolymers can be utilized as an additive in body-powder. | The polymer is also used to make Gro-Beast toys, which expand when placed in water, such as the [[Test Tube Aliens]]. Similarly, the absorbent properties of one of its copolymers can be utilized as an additive in body-powder.{{cn|date=September 2025}} | ||
It has been used | It has been used as a [[subdermal filler]] for aesthetic facial surgery {{cn|date=September 2025}} | ||
It was also used in the synthesis of the first [[Constant Viscosity Elastic (Boger) Fluids|Boger fluid]]. | It was also used in the synthesis of the first [[Constant Viscosity Elastic (Boger) Fluids|Boger fluid]].{{cn|date=September 2025}} | ||
==Environmental effects== | ==Environmental effects== | ||
| Line 152: | Line 152: | ||
Additionally, there are concerns that polyacrylamide may de-polymerise to form acrylamide. Under conditions typical for cooking, polyacrylamide does not de-polymerise significantly.<ref> | Additionally, there are concerns that polyacrylamide may de-polymerise to form acrylamide. Under conditions typical for cooking, polyacrylamide does not de-polymerise significantly.<ref> | ||
{{cite journal | vauthors = Ahn JS, Castle L | title = Tests for the depolymerization of polyacrylamides as a potential source of acrylamide in heated foods | journal = Journal of Agricultural and Food Chemistry | volume = 51 | issue = 23 | pages = 6715–6718 | date = November 2003 | pmid = 14582965 | doi = 10.1021/jf0302308 | bibcode = 2003JAFC...51.6715A }}</ref> The single claim that polyacrylamide reverts to acrylamide<ref>{{cite journal | vauthors = Smith EA, Prues SL, Oehme FW | title = Environmental degradation of polyacrylamides. II. Effects of environmental (outdoor) exposure | journal = Ecotoxicology and Environmental Safety | volume = 37 | issue = 1 | pages = 76–91 | date = June 1997 | pmid = 9212339 | doi = 10.1006/eesa.1997.1527 | url = http://www.mindfully.org/Plastic/Polymers/Polyacrylamides-Degradation1jun97.htm | access-date = 2007-11-02 | url-status = dead | archive-url = https://web.archive.org/web/20160420045005/http://www.mindfully.org/Plastic/Polymers/Polyacrylamides-Degradation1jun97.htm | archive-date = 2016-04-20 | url-access = subscription }}</ref> has been widely challenged.<ref> | {{cite journal | vauthors = Ahn JS, Castle L | title = Tests for the depolymerization of polyacrylamides as a potential source of acrylamide in heated foods | journal = Journal of Agricultural and Food Chemistry | volume = 51 | issue = 23 | pages = 6715–6718 | date = November 2003 | pmid = 14582965 | doi = 10.1021/jf0302308 | bibcode = 2003JAFC...51.6715A }}</ref> The single claim that polyacrylamide reverts to acrylamide<ref>{{cite journal | vauthors = Smith EA, Prues SL, Oehme FW | title = Environmental degradation of polyacrylamides. II. Effects of environmental (outdoor) exposure | journal = Ecotoxicology and Environmental Safety | volume = 37 | issue = 1 | pages = 76–91 | date = June 1997 | pmid = 9212339 | doi = 10.1006/eesa.1997.1527 | url = http://www.mindfully.org/Plastic/Polymers/Polyacrylamides-Degradation1jun97.htm | access-date = 2007-11-02 | url-status = dead | archive-url = https://web.archive.org/web/20160420045005/http://www.mindfully.org/Plastic/Polymers/Polyacrylamides-Degradation1jun97.htm | archive-date = 2016-04-20 | url-access = subscription }}</ref> has been widely challenged.<ref> | ||
{{cite journal | vauthors = Kay-Shoemake JL, Watwood ME, Lentz RD, Sojka RE | date = August 1998 | title = Polyacrylamide as an organic nitrogen source for soil microorganisms with potential effects on inorganic soil nitrogen in agricultural soil | journal = Soil Biology and Biochemistry | volume = 30 | issue = 8/9 | pages = 1045–1052 | doi = 10.1016/S0038-0717(97)00250-2 | bibcode = 1998SBiBi..30.1045K |url=https://naldc-legacy.nal.usda.gov/naldc/download.xhtml?id=30639&content=PDF}}</ref><ref>{{cite journal | vauthors = Gao J, Lin T, Wang W, Yu J, Yuan S, Wang S | year = 1999 | title = Accelerated chemical degradation of polyacrylamide | journal = Macromolecular Symposia | volume = 144 | pages = 179–185 | issn = 1022-1360 | doi = 10.1002/masy.19991440116 }}</ref><ref>{{cite journal | vauthors = Ver Vers LM | title = Determination of acrylamide monomer in polyacrylamide degradation studies by high-performance liquid chromatography | journal = Journal of Chromatographic Science | volume = 37 | issue = 12 | pages = 486–494 | date = December 1999 | pmid = 10615596 | doi = 10.1093/chromsci/37.12.486 | doi-access = free }}</ref> | {{cite journal | vauthors = Kay-Shoemake JL, Watwood ME, Lentz RD, Sojka RE | date = August 1998 | title = Polyacrylamide as an organic nitrogen source for soil microorganisms with potential effects on inorganic soil nitrogen in agricultural soil | journal = Soil Biology and Biochemistry | volume = 30 | issue = 8/9 | pages = 1045–1052 | doi = 10.1016/S0038-0717(97)00250-2 | bibcode = 1998SBiBi..30.1045K |url=https://naldc-legacy.nal.usda.gov/naldc/download.xhtml?id=30639&content=PDF|archive-url=https://web.archive.org/web/20210418135528/https://naldc-legacy.nal.usda.gov/naldc/download.xhtml?id=30639&content=PDF|url-status=dead|archive-date=April 18, 2021}}</ref><ref>{{cite journal | vauthors = Gao J, Lin T, Wang W, Yu J, Yuan S, Wang S | year = 1999 | title = Accelerated chemical degradation of polyacrylamide | journal = Macromolecular Symposia | volume = 144 | pages = 179–185 | issn = 1022-1360 | doi = 10.1002/masy.19991440116 }}</ref><ref>{{cite journal | vauthors = Ver Vers LM | title = Determination of acrylamide monomer in polyacrylamide degradation studies by high-performance liquid chromatography | journal = Journal of Chromatographic Science | volume = 37 | issue = 12 | pages = 486–494 | date = December 1999 | pmid = 10615596 | doi = 10.1093/chromsci/37.12.486 | doi-access = free }}</ref> | ||
Polyacrylamide is most commonly partially biodegraded by the action of [[amidase]]s, producing ammonia and [[polyacrylates]]. Polyacrylates are hard to biodegrade, but some soil microbe cultures have been shown to do so in aerobic conditions.<ref>{{cite journal | vauthors = Nyyssölä A, Ahlgren J |title=Microbial degradation of polyacrylamide and the deamination product polyacrylate |journal=International Biodeterioration & Biodegradation |date=April 2019 |volume=139 |pages=24–33 |doi=10.1016/j.ibiod.2019.02.005|s2cid=92617790 |doi-access=free |bibcode=2019IBiBi.139...24N }}</ref><!-- Article cites more recent claims of anaerobic sludges producing acrylamide, hmmmm --> | Polyacrylamide is most commonly partially biodegraded by the action of [[amidase]]s, producing ammonia and [[polyacrylates]]. Polyacrylates are hard to biodegrade, but some soil microbe cultures have been shown to do so in aerobic conditions.<ref>{{cite journal | vauthors = Nyyssölä A, Ahlgren J |title=Microbial degradation of polyacrylamide and the deamination product polyacrylate |journal=International Biodeterioration & Biodegradation |date=April 2019 |volume=139 |pages=24–33 |doi=10.1016/j.ibiod.2019.02.005|s2cid=92617790 |doi-access=free |bibcode=2019IBiBi.139...24N }}</ref><!-- Article cites more recent claims of anaerobic sludges producing acrylamide, hmmmm --> | ||
== See also == | == See also == | ||
* [[Aquamid]] | * [[Aquamid]] | ||
* [[Chitosan]] | * [[Chitosan]] | ||
* [[Rhoca-Gil]] | * [[Rhoca-Gil]] | ||
Latest revision as of 19:06, 28 November 2025
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Polyacrylamide (abbreviated as PAM or pAAM) is a polymer with the formula (-CH2CHCONH2-). It has a linear-chain structure. PAM is highly water-absorbent, forming a soft gel when hydrated. In 2008, an estimated 750,000,000 kg were produced, mainly for water treatment and the paper and mineral industries.[1]
Physicochemical properties
Polyacrylamide is a polyolefin. It can be viewed as polyethylene with amide substituents on alternating carbons. Unlike various nylons, polyacrylamide is not a polyamide because the amide groups are not in the polymer backbone. Owing to the presence of the amide (CONH2) groups, alternating carbon atoms in the backbone are stereogenic (chiral). For this reason, polyacrylamide exists in atactic, syndiotactic, and isotactic forms, although this aspect is rarely discussed. The polymerization is initiated with radicals and is assumed to be stereorandom.[1]
Copolymers and modified polymers
Linear polyacrylamide is a water-soluble polymer. Other polar solvents include DMSO and various alcohols. Cross-linking can be introduced using N,N-methylenebisacrylamide. Some crosslinked materials are swellable but not soluble, i.e., they are hydrogels.Script error: No such module "Unsubst".
Partial hydrolysis occurs at elevated temperatures in aqueous media, converting some amide substituents to carboxylates. This hydrolysis thus makes the polymer particularly hydrophilic. The polymer produced from N,N-dimethylacrylamide resists hydrolysis.Script error: No such module "Unsubst".
Copolymers of acrylamide include those derived from acrylic acid.Script error: No such module "Unsubst".
Uses
In the 1970s and 1980s, the proportionately largest use of these polymers was in water treatment.[2] The next major application by weight is additives for pulp processing and papermaking. About 30% of polyacrylamide is used in the oil and mineral industries.[1]
Flocculation
One of the largest uses for polyacrylamide is to flocculate solids in a liquid. This process applies to water treatment, and processes like paper making and screen printing. Polyacrylamide can be supplied in a powder or liquid form, with the liquid form being subcategorized as solution and emulsion polymer.Script error: No such module "Unsubst".
Even though these products are often called 'polyacrylamide', many are actually copolymers of acrylamide and one or more other species, such as an acrylic acid or a salt thereof. These copolymers have modified wetting and swellability.Script error: No such module "Unsubst".
The ionic forms of polyacrylamide has found an important role in the potable water treatment industry. Trivalent metal salts, like ferric chloride and aluminum chloride, are bridged by the long polymer chains of polyacrylamide. This results in significant enhancement of the flocculation rate. This allows water treatment plants to greatly improve the removal of total organic content (TOC) from raw water.Script error: No such module "Unsubst".
Fossil fuel industry
Script error: No such module "Labelled list hatnote". In the oil and gas industry, polyacrylamide derivatives (especially co-polymers) have a substantial effect on production by enhanced oil recovery by viscosity enhancement. High viscosity aqueous solutions can be generated with low concentrations of polyacrylamide polymers, which are injected to improve the economics of conventional water-flooding. In a separate application, hydraulic fracturing benefits from drag reduction resulting from injection of these solutions. These applications use large volumes of polymer solutions at concentration of 30–3000 mg/L.[3]
Soil conditioning
Script error: No such module "Labelled list hatnote". The primary functions of polyacrylamide soil conditioners are to increase soil tilth, aeration, and porosity and reduce compaction, dustiness and water run-off. Typical applications are 10 mg/L, which is still expensive for many applications.[3] Secondary functions are to increase plant vigor, color, appearance, rooting depth, and emergence of seeds while decreasing water requirements, diseases, erosion and maintenance expenses. FC 2712 is used for this purpose.Script error: No such module "Unsubst".
Molecular biology laboratories
Polyacrylamide is also often used in molecular biology applications as a medium for electrophoresis of proteins and nucleic acids in a technique known as PAGE. PAGE was first used in a laboratory setting in the early 1950s. In 1959, the groups of Davis and Ornstein[4] and of Raymond and Weintraub[5] independently published on the use of polyacrylamide gel electrophoresis to separate charged molecules.[5] The technique is widely accepted today, and remains a common protocol in molecular biology labs.
Acrylamide has other uses in molecular biology laboratories, including the use of linear polyacrylamide (LPA) as a carrier, which aids in the precipitation of small amounts of nucleic acids (DNA and RNA).[6][7] Many laboratory supply companies sell LPA for this use.[8] In addition, under certain conditions, it can be used to selectively precipitate only RNA species from a mixture of nucleic acids.[7]
Mechanobiology
The elastic modulus of polyacrylamide can be changed by varying the ratio of monomer to cross-linker during the fabrication of polyacrylamide gel.[9] This property makes polyacrylamide useful in the field of mechanobiology, as a number of cells respond to mechanical stimuli.[10]
Niche uses
The polymer is also used to make Gro-Beast toys, which expand when placed in water, such as the Test Tube Aliens. Similarly, the absorbent properties of one of its copolymers can be utilized as an additive in body-powder.Script error: No such module "Unsubst".
It has been used as a subdermal filler for aesthetic facial surgery Script error: No such module "Unsubst".
It was also used in the synthesis of the first Boger fluid.Script error: No such module "Unsubst".
Environmental effects
Considering the volume of polyacrylamide produced, these materials have been heavily scrutinized with regards to environmental and health impacts.[11][12]
Polyacrylamide is of low toxicity but its precursor acrylamide is a neurotoxin and carcinogen.[1] Thus, concerns naturally center on the possibility that polyacrylamide is contaminated with acrylamide.[12][13] Considerable effort is made to scavenge traces of acrylamide from the polymer intended for use near food.[1]
Additionally, there are concerns that polyacrylamide may de-polymerise to form acrylamide. Under conditions typical for cooking, polyacrylamide does not de-polymerise significantly.[14] The single claim that polyacrylamide reverts to acrylamide[15] has been widely challenged.[16][17][18]
Polyacrylamide is most commonly partially biodegraded by the action of amidases, producing ammonia and polyacrylates. Polyacrylates are hard to biodegrade, but some soil microbe cultures have been shown to do so in aerobic conditions.[19]
See also
- Aquamid
- Chitosan
- Rhoca-Gil
- Sodium polyacrylate, a similar material
References
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